The present invention relates to a damping structure, a spindle supporting box structure, a gas supply related device, and a balance cylinder gas actuated device for machine tools. The damping structure may be a general structure or a partial structure for machine tools.
A base as one unit of a structure for machine tools and a column as a box structure for supporting a spindle are designed to have little mechanical vibration in order to increase workability for machine tools.
Therefore, components of the base and column are thickened, or provided with reinforcing ribs to increase the rigidity thereof.
Especially in a column which supports a spindle to move up and down, keeping the rigidity of the column is important. A conventional example is shown in FIGS. 10A and 10B. FIG. 10A is a perspective view of a column to which a spindle is mounted so as to move up and down. FIG. 10B is a horizontal cross sectional view of the upper part of the column.
As shown in these figures, the column is generally formed by assembling plate members. Namely, flat plates 11a, are fixed to longitudinal side faces 11a, 11b, 11c, and 11d, respectively, and then connected with each other. Besides, longitudinal ribs 102 and lateral ribs 103 are fixed to the inside of each flat plate 101, thereby increasing the of the whole column rigidity.
Reference number 12 is a spindle device having a spindle 12b. The spindle device 12 comprises a supporting guide base 12a, and a spindle driving motor which is not shown here. Rails 14, 14 fixed on the front side face plate 11a are guiding the spindle device 12 up and down by means of the supporting guide base 12a. The spindle device 12 is actuated up and down by an unshown driving device.
The above means such as thickening components or adding reinforcing ribs to increase rigidity have a high cost. Therefore, recently outer peripheries of base components are surrounded by plates, and then concrete is filled therein. Or, concrete blocks are fixed to required parts afterwards.
In a small machine tool, it is easy to surround outer peripheries of a base with plates and fill concrete therein. However, in a big machine tool, it is troublesome or sometimes rather unsuitable. Besides, as years go by, concrete is constricted due to water evaporation, and breaks away from the plates, thereby decreasing rigidity as well as causing noise.
Moreover, fixing concrete blocks afterwards is generally troublesome. Besides, as described above, concrete changes as years go by, thereby distorting a structure and decreasing machine accuracy.
On the other hand, as shown in FIGS. 11A and 11B, there is a column wherein slits s, s are formed at front and back longitudinal side faces 11a, 11b, respectively, and wherein a spindle 12b is mounted across the slits s, s so as to move up and down.
FIG. 11A is a perspective view of a column to which a spindle is mounted, and FIG. 11B is a horizontal cross sectional view of the upper part of the column.
In the column shown in these figures, the front and back longitudinal side faces 11a, 11b can not keep strong rigidity, and the connection between right and left longitudinal side faces 11c, 11d seems to break away, thereby causing a lack of rigidity of the whole column.